Muscle Physiology
Teacher’s Guide
By Susan B. Parsons (NSF GK-12 Idaho State/Marsh Valley High)
Lesson Overview: Discuss basic structure of muscle, muscle enervation,
and the physiology of aerobic contraction, anaerobic contraction, and
muscle fatigue. Perform exercises (rock-climbing) and explain
experiences/sensations in terms of muscle structure and function.
Subject Area:
Biology, Anatomy and
Physiology
Topic: Skeletal Muscle
National Science Education Standards Addressed:
Audience: AP Biology,
Advanced Anat. & Phys
Suggested time: 3 hrs
Resources:
Human Anatomy and physiology text
PowerPoint Presentation muscle_phys
Materials:
Climbing Wall, safety
equipment, and
facilitation.
Worksheet
Learning Objectives:
1. Be able to describe and identify the general anatomy of skeletal muscle down to the level of a
sarcomere, and the proteins and structures associated with sarcomeres.
2. Understand the role of neurotransmitters, action potentials, membrane polarization, and ion
concentration/movement in muscle enervation.
3. Understand the role of contractile fibers, the tropin-tropomysoin complex, calcium, and ATP in
sarcomere contraction.
4. Be able to explain the difference between aerobic vs. anaerobic muscle contraction, energy
utilization, and the accumulation of metabolic by-products.
Background:
Muscle contraction is required for movement, support, and functioning of the musculoskeletal
system. The basic unit of skeletal muscle contraction is the sarcomere, where contractile fibers move
past each other in a ratcheting fashion. The ratcheting action of these contractile fibers make it possible
for muscles to shorten, and through their attachment to bones, cartilage, and other muscles, pull the
skeleton into various positions.
This lesson is unique in that students will get to experience the sensations of muscle fatigue and
interpret them in terms of anaerobic vs. aerobic exercise, the accumulation of metabolic by-products
(lactic acid) as the ATP demands of anaerobic muscle contraction increases, and the overall role of ATP
in the sarcomere being that it knocks myosin heads off of actin binding sites. This is important, as
stressed muscles will feel firm to the touch because they have been depleted of ATP reserves, not
allowing the myosin heads to be removed from actin and maintaining a partially contracted state after
exercise has stopped. Rock climbing exercises are particularly useful in demonstrating these principles,
as it is largely anaerobic, quickly results in muscle fatigue and failure, and characteristically causes
tightness and soreness in the forearms due to muscle fatigue.
Assessment Strategy:
1. Students will be tested on their mastery of lecture content.
2. Students will be required to complete a worksheet designed to assess their ability to apply
lecture material to their experiences of muscle physiology and fatigue.
Teaching Tips:
1. Lecture on skeletal muscle and function, and review aerobic vs. anaerobic respiration in the
class period(s) preceding the rock climbing exercise.
2. Emphasize the importance of following safety procedures while using rock climbing wall and
equipment.
3. Have students perform the activities described on the worksheet during their visit to the rock
climbing wall. Be sure that they are actually doing the lab and answering the associated
questions, and not simply ‘goofing around.’
4. Go over worksheet as a class following the exercise.
References:
Shmaefsky, Brian R. 2007. Applied Anatomy and Physiology: A Case Study Approach. Paradigm
Publishing Inc.
Muscle physiology
Checklist:
Climb on a vertical or under-vertical wall.
Climb on a steep or over-hung wall.
Practice keeping your arms straight, rather than keeping your biceps flexed, while searching for
the next hold.
Climb until you become so exhausted that your muscles fail, and you fall off the wall.
Massage you forearms after an especially exhausting climb.
Questions:
1. Describe how your arms felt after climbing on a vertical or under-vertical wall with large holds,
vs. a very steep or over-hung wall with small holds. Why is there a difference?
2.
How does resting in a straight-arm posture while searching for the next move conserve energy?
3. What is causing the burning sensation in your arm muscles upon fatigue and why?
4. Describe the texture of your forearms after a climb, are they firm or soft? Why do they become
firm and hard to the touch after prolonged physical exertion?
5. Why would massaging a muscle alleviate some of the symptoms of fatigue and over-exertion?